Historical-material and virtual reconstruction for the conservation of the San Juan Bautista Renaissance Altarpiece (Antequera, Spain)

Abstract

The City of Antequera Service of Movable Property Restoration carries out an action program that includes the Project of the Altarpiece of San Juan Bautista Conservation-Restoration in the San Zoilo Church (Antequera, Andalusia-Spain). This project focuses on the conservation, assembly and recovery of the altarpiece in its origin place (side wall of the Comulgatorio chapel). The authors have participated in research about the historical-material and virtual reconstruction of the altarpiece and have contributed to its recovery and enhancement.

The San Juan Bautista altarpiece was made around the end of the 16^th century, in gilded and polychrome wood. Its architectural box structure is decorated with 18 paintings on a panel and an exempt sculpture. Its Renaissance style shows carved and polychrome decorations based on fauna and fantastic figures, medallions, foliage, and cherubs. It stands out for being one of the few Renaissance examples that are preserved in the city of Antequera, against the primacy of the Baroque and Pseudoclassicist style altarpieces. The paintings on the panel are masterfully executed and narrate episodes of the life of the Virgin plus the life and passion of Christ; it also represents saints related to the Franciscan order that founded the old convent (San Francisco and Santa Clara). The central sculpture depicts St. John the Baptist (c. 1550). Currently, it is exhibited in the city's museum. The sculpture has been repolychromed several times, showing a stylistic discordance with respect to the decoration and tables that adorn the altarpiece. The construction system of the altarpiece is classified as mixed. The structure has a self-supporting system. The architectural elements make up the box. It is assembled from the bottom up. It is dismantled in the opposite direction and incorporates some elements that anchor it to the wall. It measures about 5.25 m x 3.77 m (height x width).  It consists of five streets in a vertical direction, where the central one protrudes slightly in height with respect to the adjoining sides. Horizontally, the space is distributed in sotobanco, bench or predella, first body, second body and attic.

When the research first started, the altarpiece was fragmented, dispersed, and decontextualized from its original environment due to various vicissitudes. The different fragments into which it was divided during its dismantling had divergent destinations in terms of their material history. Most of them were stored at the town hall. Also, the paintings on panel and sculpture of the first body, after a deep restoration, were exhibited in the Municipal Museum of the city of Antequera.

The objectives of this article are: first, to expose the methodology and results obtained after the technical study of the different fragments that make up the altarpiece; second, to reconstruct its history-material to elucidate the circumstances by which it was dismantled and decontextualized from its surroundings; finally, to reconstruct graphically and virtually the altarpiece from the existing fragments to highlight the losses of some of them; in so doing, the authors tried to demonstrate the viability of the final assembly process of the altarpiece in its original environment. Through documentary (bibliographic and graphic) and virtual (photogrammetry, orthophotography, and 3D) techniques, answers to the following questions were sought: Why is the altarpiece dismantled? When is it produced? When are the original pieces that are missing lost or stolen? Are all pieces preserved? How many fragments were divided during the physical disassembly process? Is the state of conservation of the existing fragments homogeneous? The conclusions obtained indicate that the physical dismantling took place between 1973 and 1983, due to the continuous deterioration of the building; the altarpiece itself became more evident in the linear support and tow of the predella boards. It was divided into forty fragments, which are still preserved. The plundering of original parts (two predella boards, first and central) is confirmed as prior to 1899. Finally, it should be noted that the current image of the altarpiece shows a visual dissonance that will hinder its conservation-restoration intervention.